Anti-corrosion and wear-resistant method for surface of flow passage component of centrifugal pump

Abstract

The invention provides an anti-corrosion and wear-resistant method for the surface of a flow passage component of a centrifugal pump. The method comprises the steps that the surface of the flow passage component of the centrifugal pump is purified; roughening the surface of the flow passage component of the centrifugal pump; preheating the surface of the flow passage component of the centrifugal pump; a plasma spraying process and a special-shaped part spraying device are adopted for spraying treatment on the flow passage component, and an oxidized ceramic material for spraying comprises the following raw materials in percentage by mass: 92% of Cr2O3 powder and 8% of TiO2 powder; and post-treatment is conducted on the surface of the centrifugal pump flow passage component obtained after the coating is sprayed. By optimizing the technological process and improving the spraying device and the coating material, the corrosion resistance and wear resistance of the surface of the flow passage component of the centrifugal pump are improved.

Description

Technical Field

[0001] This invention belongs to the field of powder cleaning hole sealing technology, and specifically relates to a method for corrosion prevention and wear resistance of the surface of flow components of a centrifugal pump. Background Technology

[0002] Centrifugal pump flow components include the pump cover, guide vanes, impeller, inducer, and pump casing. Their materials are selected according to API 610, "Centrifugal Pumps for the Petroleum, Petrochemical, and Natural Gas Industries." These flow components primarily convert the kinetic energy of the impeller's high-speed rotation into hydraulic pressure energy, which is then transported to the high-pressure reactor. The main principle is that the high-speed rotation of the impeller generates centrifugal force, drawing liquid in from the center and throwing it outwards, thus converting the impeller's kinetic energy into the liquid's kinetic energy. After entering the guide vanes, the high-speed liquid further converts its kinetic energy into pressure energy through the diffuser channel, thereby achieving the transport of liquid from the low-pressure zone to the high-pressure zone. Extending the service life of centrifugal pump flow component materials under extreme conditions such as particle content, high temperature, and strong corrosion has become an important research topic.

[0003] Surface treatment technology for reinforcing and protecting substrate materials has advantages such as fewer limiting factors and a wide range of applications, thus this method has been increasingly used in scientific research and actual production processes. Plasma spraying, as a surface treatment technology, has advantages such as wide applicability, high processing efficiency, and good coating surface quality, playing an increasingly important role in the surface reinforcement of substrate materials. To improve the wear of materials in the flow-through components of centrifugal pumps, while considering the requirements of media corrosivity, temperature, pressure, operating costs, and processing performance, surface treatment technology for reinforcing and protecting the substrate materials of flow-through components is particularly important. Oxide ceramic materials, with their high-temperature oxidation resistance, corrosion resistance, wear resistance, chemical stability, and high hardness, have become an ideal choice for plasma spraying materials. However, current research mainly focuses on preparation processes, coating materials, and experimental verification. Research on the spraying of key components in chemical equipment and the improvement of spraying equipment is still limited, especially for the petrochemical industry, where there is a lack of systematic research on spraying equipment and processes for key components requiring high hardness and corrosion resistance. Summary of the Invention

[0004] To address the challenges in existing technologies, the inventors have conducted in-depth research and developed a method for corrosion and wear resistance of the surface of centrifugal pump flow components. By optimizing the process flow, improving the spraying equipment and coating materials, the corrosion and wear resistance of the centrifugal pump flow components is enhanced.

[0005] The technical solution provided by this invention is as follows: In a first aspect, a method for corrosion and wear resistance protection of the surface of a centrifugal pump flow-through component includes the following steps: Cleaning treatment of the surface of the flow-through components of the centrifugal pump; Surface roughening treatment of the flow-through components of the centrifugal pump; Preheating treatment of the surfaces of the flow-through components of the centrifugal pump; The flow-through components are coated using a plasma spraying process. The oxide ceramic material used for spraying includes the following raw materials by mass percentage: 92% Cr2O3 powder and 8% TiO2 powder. Post-treatment is performed on the surface of the centrifugal pump flow parts after the coating is applied.

[0006] Secondly, a special-shaped parts spraying device includes an anode unit, a cathode unit, a powder injection channel, a working gas inlet, and a spray gun cavity; a strip-shaped powder injection channel is opened in the housing on one side of the spray gun cavity, and a plurality of spraying ports penetrating the housing are opened on the strip-shaped powder injection channel. The anode unit and cathode unit are located inside the spray gun cavity and are connected to an external power source. The anode unit includes multiple connected anode nozzle units, and the cathode unit includes multiple connected cathode units. The anode nozzle units and cathode units correspond one-to-one to form multiple plasma arc generating units. The plasma arc generating units are aligned with the spray nozzles on the strip-shaped powder injection channel. The working gas enters the spray gun chamber through the working gas inlet and is ignited by the power supply to form a plasma arc. The powdered oxide ceramic material is sent into the plasma flame through the powder injection channel and heated to a molten state to form molten oxide ceramic particles. After being sprayed out at high speed, the particles impact the surface to be sprayed, forming a plasma spray coating.

[0007] The present invention provides a method for corrosion and wear resistance protection of the surface of a centrifugal pump flow component, which has the following beneficial effects: (1) The present invention proposes a method for corrosion and wear resistance of the surface of the flow-through components of a centrifugal pump, namely, using plasma spraying technology to treat the surface of the flow-through components. Since the surface of the flow-through components has structures such as planes, spatial cones, spatial curved surfaces, and circular holes, traditional surface treatment methods are difficult to achieve uniform treatment of the above structures. The plasma spraying device of the present invention for spraying the surface of irregular parts can uniformly spray thermal spraying powder onto the surface of the flow-through components according to the actual structure at a certain feeding rate, spraying distance, spraying speed, and spraying angle, striving to make the flight path of the powder perpendicular to the substrate surface, thereby forming a high-quality thin film coating with wear and corrosion resistance that meets the design requirements in terms of thickness and density, high bonding strength, high hardness, and low porosity.

[0008] (2) The present invention proposes a method for corrosion and wear resistance of the surface of the flow part of a centrifugal pump. The method uses a new type of spraying material Cr2O3+TiO2 with a melting point of 2266℃, which has higher heat resistance than traditional oxide ceramics; the hardness value is 1298.6 HV, which is 5-10% higher than that of traditional plasma ceramic coatings; the introduction of TiO2 improves the process performance of powder spraying, increases the deposition efficiency of sprayed powder, and increases the bonding force with the substrate. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of the flow-through components of a centrifugal pump. Figure 2 This is a schematic diagram of the guide vane coating surface; Figure 3 This is a schematic diagram of the sprayed surface of the pump cover; Figure 4 This is a schematic diagram of impeller spraying. Figure 5 This is a schematic diagram of the induction wheel spraying process; Figure 6 Flowchart of a method for corrosion and wear resistance protection of the surface of flow-through components of a centrifugal pump; Figure 7 A schematic diagram of a spraying device for irregularly shaped parts; Figure 8 This is a schematic diagram of spraying the guide vane surface using a non-standard parts spraying device. Detailed Implementation

[0010] The features and advantages of the present invention will become clearer and more explicit from the following detailed description.

[0011] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0012] This invention provides a method for corrosion and wear resistance protection of the surface of centrifugal pump flow components. By using a special-shaped parts spraying device, it improves the problems of uneven coating, low production efficiency, difficulty in mass production, and limitations imposed by the size of the spraying equipment on the surface of irregularly shaped parts (such as conical, curved, and cylindrical parts). It provides a spraying process for coatings that enhance the hardness, corrosion resistance, and heat resistance of the centrifugal pump flow components. Combining the advantages of atmospheric plasma spraying technology, the prepared coating has a dense structure, low oxide content and porosity, strong adhesion between the coating and the substrate, high equipment control precision, wide powder coverage, and a friendly working environment. Simultaneously, it selects oxide ceramics as the coating material, which have high hardness, low coefficient of friction, good wear and corrosion resistance, good fluidity, a certain metallic luster, good physical properties, are insoluble in water and difficult to dissolve in acids, and are extremely stable in light, air, high temperature, and corrosive gas environments. By using a spraying tool to spray the surface of the flow-through components of a centrifugal pump, a high-hardness and high-corrosion-resistant high-quality coating is prepared on the surface of the flow-through components, effectively meeting the anti-corrosion and wear-resistant requirements of the centrifugal pump flow-through components and improving their performance and service life.

[0013] Figure 1 is a schematic diagram of the flow-through components of a centrifugal pump. These components include: pump cover 1, guide vanes 2, impeller 3, inducer 4, and pump casing 5. The flow-through components primarily convert the kinetic energy of the high-speed rotation of the impeller 3 into hydraulic pressure energy, which is then transported to the high-pressure reactor. The main principle is that the high-speed rotation of the impeller 3 generates centrifugal force, drawing liquid in from the center and throwing it outwards, thus converting the kinetic energy of the impeller 3 into the kinetic energy of the liquid. After the high-speed liquid enters the guide vanes 2, the kinetic energy is further converted into pressure energy through the diffuser channel, thereby achieving the transport of liquid from the low-pressure zone to the high-pressure zone.

[0014] Figures 2-5 are schematic diagrams of the parts of each flow-through component that require spraying. Figure 2 shows the guide vane spraying surface, which includes a spatial annular surface 21, a conical surface 22, and a circumferential cylindrical surface 23; Figure 3 shows the pump cover spraying surface, which is the pump cover annular surface 11; Figure 4 shows the impeller spraying surface, which includes the blade surface 31 and the rear cover plate surface 32 that contacts the blade. Figure 5 The coating surfaces of the inducer wheel are the conical shaft surface 41 of the inducer wheel and the pressure and suction surfaces 42 of the inducer wheel blades.

[0015] like Figure 6 As shown, the present invention provides a method for corrosion and wear resistance protection of the surface of a centrifugal pump flow component, comprising the following steps: (1) Parts processing: The flow parts are processed to the specified dimensions according to the drawings and the relevant final heat treatment is carried out. The influence of coating thickness on the size of the spraying position should be fully considered, and the coating thickness should be uniformly transitioned at the junction.

[0016] (2) Surface cleaning treatment: The surface of the substrate material will inevitably be oxidized or come into contact with grease. The substrate needs to be cleaned and pretreated before spraying.

[0017] (3) Surface roughening treatment: The roughening treatment of the substrate surface mainly adopts sandblasting roughening and electrical discharge roughening; the roughening treatment is mainly to increase the roughness of the contact surface between the coating and the substrate, so as to improve the bonding strength between the coating and the substrate surface.

[0018] (4) Preheating treatment: Preheating treatment is the final step in the surface pretreatment process and is usually carried out before spraying. It aims to bring the workpiece surface to a suitable temperature and keep it fresh.

[0019] (5) Spraying anti-corrosion and wear-resistant layer: Plasma spraying process is used to spray the flow parts. Before spraying, the powder must also be preheated and dried in a drying oven. The purpose is to increase the flowability of the sprayed powder and ensure the spraying quality.

[0020] To address the problems of uneven surface coating and low production efficiency on irregularly shaped parts, this invention provides a coating device for irregularly shaped parts, such as... Figure 7As shown, it includes: an anode unit 64, a cathode unit 66, a powder injection channel 63, a working gas inlet 65, and a spray gun cavity 67; a strip-shaped powder injection channel 63 is opened in the housing on one side of the spray gun cavity 67, and several spray nozzles penetrating the housing are opened on the strip-shaped powder injection channel 63. The anode unit 64 and cathode unit 66 are located inside the spray gun cavity 67 and are connected to an external high-frequency power supply. The anode unit 64 includes multiple connected anode nozzle units, and the cathode unit 66 includes multiple connected cathode units. The anode nozzle units and cathode units correspond one-to-one to form multiple plasma arc generating units. The plasma arc generating units are aligned with the spray nozzles on the strip powder injection channel 63. The working gas enters the spray gun chamber 67 through the working gas inlet 65 and is ignited by a high-frequency power supply to form a plasma arc. Powdered oxide ceramic material is fed into the plasma flame through the powder injection channel 63 and heated to a molten state to form molten oxide ceramic particles 62. These particles are then ejected at high speed and impact the surface 61 to be coated. They adhere to the substrate surface and accumulate to form a plasma spray coating of a certain thickness. This irregular part spraying device acts as a plasma arc generator, generating a high-temperature, high-speed plasma flame to melt and accelerate the spray powder into the flame, ultimately spraying it onto the substrate surface. The cathode unit 66 is the electron emission source and is made of tungsten, a material with a high melting point and strong electron emission capability. The anode unit 64 is a key and easily worn component of the spray gun. It is made of copper with good thermal conductivity. The working gas needs to pass through a water-cooled nozzle to compress the arc and generate the plasma arc.

[0021] The irregular part spraying device includes multiple plasma arc generating units. When spraying ceramic coatings on the surface of irregular parts, it can spray around the surface of the parts from multiple angles to improve the uniformity of spraying.

[0022] The oxide ceramic material comprises the following raw materials by mass percentage: 92% Cr2O3 powder and 8% TiO2 powder. Because pure Cr2O3 has low deposition efficiency, 8% TiO2 is added by mass to improve the powder coating process performance, increase the deposition efficiency of the sprayed powder, and enhance the adhesion to the substrate. The oxide ceramic material possesses excellent physical properties such as high hardness, low coefficient of friction, good wear and corrosion resistance, and good flowability. It is insoluble in water and difficult to dissolve in acids, and is extremely stable in light, air, high temperature, and corrosive gas environments. This novel oxide ceramic material has a melting point of 2266℃, exhibiting higher heat resistance than traditional oxide ceramics; its hardness value is 1298.6 HV, which is 5-10% higher than traditional plasma ceramic coatings.

[0023] Conventional plasma spray guns struggle to coat the internal surfaces of irregularly shaped parts because they spray axially, preventing the adjustment of plasma direction and angle. This results in a masking effect when spraying the inner walls or holes of irregularly shaped parts, as the spray gun barrel forms an angle with the substrate surface. Furthermore, the powder is not sprayed perpendicularly to the workpiece surface, leading to suboptimal coating quality. Developed coating equipment for irregularly shaped parts ensures that powder is sprayed perpendicularly to the workpiece surface, improving coating quality and space utilization. This equipment can be used for coating both the internal and external surfaces of irregularly shaped parts. See [link to equipment]. Figure 8 .

[0024] (6) Post-coating treatment: Post-coating treatment methods include heat treatment after coating, resin sealing treatment after coating, and surface processing after sealing. Using epoxy resin sealing materials and sealing processes can effectively seal defects such as pores inside the coating, resulting in better corrosion resistance and longer corrosion resistance under the same usage conditions.

[0025] Example A method for corrosion and wear resistance protection of the surface of a centrifugal pump flow component includes the following steps: The first step is to process the parts. According to the drawings, the flow-through components are processed to the specified dimensions and then subjected to relevant final heat treatment. The influence of coating thickness on the dimensions of the spraying position should be fully considered, and the coating thickness should be uniformly transitioned at the interface. The second step is surface cleaning treatment. Ultrasonic degreasing is used on the surfaces of the flow parts that need to be sprayed in Figures 2-5. That is, high-frequency sound waves with a frequency of more than 16 kHz are used for degreasing to improve work efficiency. The third step is surface roughening treatment, which is carried out by sandblasting using 60-mesh white corundum at a distance of 200 mm and a sandblasting air pressure of 0.6-0.8 MPa.G. This increases the roughness of the contact surface between the coating and the substrate, resulting in a higher bonding strength between the coating and the substrate, approximately 10-15% higher than that of traditional plasma treatment. The fourth step is preheating, which is usually carried out before spraying. The purpose of preheating is to bring the surfaces of the flow-through components in Figures 2-5 to a suitable temperature and keep them fresh. The preheating temperature is maintained between 80°C and 120°C. The fifth step is to apply the anti-corrosion and wear-resistant layer: This involves using plasma spraying technology and a special-shaped parts spraying device to apply the coating to Figure 2 - Figure 5Each flow-through component in the process is sprayed. Before spraying, the powder is preheated and dried in a drying oven. Gas (usually hydrogen or nitrogen, sometimes with the addition of argon or helium to achieve higher temperatures) is introduced into the spray gun chamber as shown in Figure 7. It is ionized into high-temperature ion gas through high-frequency ignition and ejected at high speed through the anode nozzle. The oxide ceramic powder is fed into the plasma flame by a carrier gas to melt and accelerate, and is uniformly sprayed onto the workpiece surface at a specific spraying speed. When spraying the surfaces shown in Figure 2, a rotating device is used to ensure uniformity and coverage of the spray, and smooth transitions are ensured at all junctions. The sixth step is post-coating treatment. After sealing the pores of the coating with epoxy resin, the coatings of each flow-through component in Figures 2-5 are subjected to rough grinding, fine grinding, and polishing according to the dimensions, tolerances, and roughness requirements specified in the drawings. After processing, the coating thickness meets different design requirements based on the actual operating conditions. The seventh step is coating inspection: check whether the coating area, hardness, thickness, and porosity meet the design requirements. If any discrepancies are found, the coating needs to be cleaned, polished, and recoated. The prepared ceramic coating has a porosity of <2.5%, which is approximately 20%-30% lower than that of traditional plasma ceramic coatings.

[0026] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

[0027] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A method for corrosion and wear resistance on the surface of a centrifugal pump flow-through component, characterized in that, Includes the following steps: Cleaning treatment of the surface of the flow-through components of the centrifugal pump; Surface roughening treatment of the flow-through components of the centrifugal pump; Preheating treatment of the surfaces of the flow-through components of the centrifugal pump; The flow-through components are coated using a plasma spraying process. The oxide ceramic material used for spraying includes the following raw materials by mass percentage: 92% Cr2O3 powder and 8% TiO2 powder. Post-treatment is performed on the surface of the centrifugal pump flow parts after the coating is applied.

2. The method for corrosion protection and wear resistance of the surface of the flow-through components of a centrifugal pump according to claim 1, characterized in that, The step of using plasma spraying to spray the flow-through components includes using a special-shaped parts spraying device to spray the flow-through components. The special-shaped parts spraying device includes: an anode unit, a cathode unit, a powder injection channel, a working gas inlet, and a spray gun cavity; a strip-shaped powder injection channel is opened in the housing on one side of the spray gun cavity, and several spraying ports that penetrate the housing are opened on the strip-shaped powder injection channel. The anode unit and cathode unit are located inside the spray gun cavity and are connected to an external power source. The anode unit includes multiple connected anode nozzle units, and the cathode unit includes multiple connected cathode units. The anode nozzle units and cathode units correspond one-to-one to form multiple plasma arc generating units. The plasma arc generating units are aligned with the spray nozzles on the strip-shaped powder injection channel. The working gas enters the spray gun chamber through the working gas inlet and is ignited by the power supply to form a plasma arc. The powdered oxide ceramic material is sent into the plasma flame through the powder injection channel and heated to a molten state to form molten oxide ceramic particles. After being sprayed out at high speed, the particles impact the surface to be sprayed, forming a plasma spray coating.

3. The method for corrosion protection and wear resistance of the surface of the centrifugal pump flow components according to claim 2, characterized in that, The cathode unit is made of tungsten; the anode unit is made of copper.

4. The method for corrosion protection and wear resistance of the surface of the flow-through components of a centrifugal pump according to claim 1, characterized in that, The surface roughening treatment of the centrifugal pump flow parts includes sandblasting and electrical discharge machining.

5. The method for corrosion protection and wear resistance of the surface of the centrifugal pump flow components according to claim 1, characterized in that, The post-treatment steps for the centrifugal pump flow components after spray coating include: heat treatment after coating, resin sealing treatment after coating, and surface processing after sealing.

6. A spraying device for irregularly shaped parts, characterized in that, The irregular part spraying device includes an anode unit, a cathode unit, a powder injection channel, a working gas inlet, and a spray gun cavity; a strip-shaped powder injection channel is opened in the housing on one side of the spray gun cavity, and several spraying ports that penetrate the housing are opened on the strip-shaped powder injection channel; The anode unit and cathode unit are located inside the spray gun cavity and are connected to an external power source. The anode unit includes multiple connected anode nozzle units, and the cathode unit includes multiple connected cathode units. The anode nozzle units and cathode units correspond one-to-one to form multiple plasma arc generating units. The plasma arc generating units are aligned with the spray nozzles on the strip-shaped powder injection channel. The working gas enters the spray gun chamber through the working gas inlet and is ignited by the power supply to form a plasma arc. The powdered oxide ceramic material is sent into the plasma flame through the powder injection channel and heated to a molten state to form molten oxide ceramic particles. After being sprayed out at high speed, the particles impact the surface to be sprayed, forming a plasma spray coating.

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